1. Field of the Invention
The invention relates generally to improvements in pusher cylinders for use with glassware forming machines for moving finished glassware articles from an associated dead plate onto a moving conveyor.
2. Description of the Prior Art
Pusher mechanisms for moving glassware articles from a dead plate to a moving conveyor are well known in the prior art. These devices generally include a pneumatic pusher cylinder or head and a rotary actuator means for moving it through a predetermined arcuate path. In operation each pusher cylinder piston is extended, prior to the deposition of one or more glassware articles on a corresponding dead plate, in order to have the fingers be adjacent to the deposited bottles. Extention of the piston rod end is by conventional pneumatic means and positions fingers at the end of the piston rod near the glassware articles. Movement of the pusher cylinder through an arcuate path is an operating stroke which causes the fingers to contact the ware and move it outwardly through an angle of approximately 90.degree. onto a moving conveyor. The piston rod is then retracted and the pusher cylinder returned inwardly on a return stroke in the opposite arcuate direction to complete the cycle.
Pusher cylinders must be adjusted from time to time in order to change the piston stroke length to accommodate different size ware. The piston stroke length adjustment means used in prior art pusher cylinders is generally cumbersome and inefficient. These adjustment means generally utilize mechanical stops to restrict piston stroke length and are thus obviously greatly subject to wear. Such stops may comprise, for example, stop nuts on a shaft external to the cylinder housing (as shown in U.S. Pat. No. 4,340,413) or a stop nut on a threaded rod coaxially aligned within a guide post in a piston (as shown in U.S. Pat. No. 3,559,537).
Also, prior art pusher cylinders use a variety of means to counteract the tendency of the moment arm created by the pusher fingers to cause the piston to rotate when it is extended: double parallel cylinders (U.S. Pat. No. 4,340,413), parallel guide rods (U.S. Pat. Nos. 4,203,752 and 3,559,537). These are relatively costly arrangements that are also subject to wear as well as differential thermal expansion which limits efficiency over a wide operating temperature range.
Accordingly, it is an object of this invention to produce a pusher cylinder having a more efficient stroke length adjustment means. It is yet another object of this invention to produce a pusher cylinder having a unique guide means to resist its rotational tendencies.